The San Diego traffic court threw out a citation against Cecilia Abadie, with commissioner John Blair ruling she was not guilty because the offence for which was ticketed requires proof that the device was in use.

Mr Blair found there was no proof beyond a reasonable doubt.

Ms Abadie, who was also found not guilty of speeding, is believed to be the first motorist cited for wearing Google Glass while driving.

The software developer said she was among around 30,000 people called "explorers" selected to try out Google Glass before the technology becomes widely available to the public later this year.

The device, on a kind of glasses frame, features a thumbnail-size transparent display above the right eye.

The lightweight frames are equipped with a hidden camera and tiny display that responds to voice commands. The technology can be used to do things such as check email, learn background about something the wearer is looking at, or to get driving directions.

At least three states - Delaware, New Jersey and West Virginia - have introduced bills that would ban driving with Google Glass.

Google's website contains an advisory for users: "Read up and follow the law. Above all, even when you're following the law, don't hurt yourself or others by failing to pay attention to the road."

Ms Abadie was stopped on a San Diego freeway in October. The California Highway Patrol officer saw she was wearing Google Glass and tacked on a citation usually given to people driving while a video or TV screen is on in the front of their vehicle.

Ms Abadie pleaded not guilty to both charges and her lawyer William Concidine said previously the device was not activated when she was driving.

At the time of Ms Abadie's citation, the highway patrol said anything that took a driver's attention from the road was dangerous.

AP

Ms Abadie said she was happy she won her case but hoped the court would rule that Google Glass was legal to wear while driving, whether activated or not.

"I believe it's an initial success but we have a long way to go," she said.

Google said today it has warned early Glass adopters to exercise caution.

"Glass is built to connect you more with the world around you, not distract you from it," it said.

"Explorers should always use Glass responsibly and put their safety and the safety of others first."